This invention relates to a water feed system at a constant temperature keeping the hot water from mixing with the cold water fed during use of hot water, particularly to a water feed system adapted to heat storage type hot water tank of flushing type toilet, electric water heater and drinking machine. During use of the hot water, the cold water is firstly fed into closed flexible means in a single hot water tank. The flexible means will then lower down, as the cold water increases and the hot water decreases. Upon nonuse of hot water, the cold water discharging tube is caused to open by the control circuit. Under the external force, the cold water stored inside the closed means will flow out of the discharging tube into the hot water tank whereby the hot water is kept from mixing with the cold water fed during use of the hot water.
The conventional water heater which electrically heats the cold water, for example, the heat storage type hot water tank of the flushing type toilet, provides a cold water feed system in which upon flushing with the hot water, the cold water is made up into the hot water tank. After a lapse of long while for continual use, the cold water will increase while the hot water will decrease, as a result of which the water thus mixed will get colder. To solve this problem, an electric current and a voltage of greater power ratio are used to instantaneously heat. For they use specific high voltage and electric current, the drawbacks such as the complicacy in fitting, the difficulty in execution, the costliness in enlarging the equipment, the highness in the failure rate of the equipment and the lack in safety due to the overload of electric current are apparent. As to drinking machine, while the cold water and the hot water may be respectively used, a cold water tank and a hot water tank are required, as a result of which the volume of the machine will increase to occupy a larger space and the cold water insufficient for a long time will cause an adverse effect.
To obviate the above drawbacks, this invention provides a single tank type water feed system keeping the hot water from mixing immediately with the cold water fed during use of the electrically heated water wherein closed means is provided on the upper portion inside the single tank hot water container for the cold water to feed therein during use of the hot water, at the same time of which a control circuit actuates the electromagnetic valve in the discharging tube to a closed position; upon nonuse of the hot water, the control circuit actuates the electromagnetic valve in the discharging tube to an open position, whereby the effect of the external force applied upon the cold water stored in advance in the closed means decreases and the cold water is fed into the hot water storage tank from the discharging tube communicated with the closed means. After the closed space is totally compressed, that is, after the cold water in the flexible space is totally pushed into the hot water storage tank, the cold water will stop feeding, and the cold water fed will be heated by the heater to maintain the hot water within a predetermined temperature. Therefore, the cold water will not mix with the hot water during use of the hot water. And upon nonuse of the hot water, the cold water is fed again and heated to a predetermined temperature so as to be ready for use.